Method and system for dynamic optimization of a time-domain frame structure

ABSTRACT

A method at a network element, and a system, for resource reservation in an unlicensed spectrum band. The method includes determining quality of service requirements of traffic queued for a network operator. Further, the method includes reserving resources in the unlicensed spectrum band for the network operator in accordance with the quality of service requirements to form a coordination frame for the traffic, where the coordination frame has a flexible proportion of the resources from the unlicensed spectrum.

FIELD OF THE DISCLOSURE

The present disclosure relates to mobile communications and inparticular relates to mobile communications utilizing unlicensedspectrum.

BACKGROUND

Wireless data usage has experienced, and continues to experience,significant growth. Some estimates provide for growth in data usageexceeding one thousand times current usage in the near future.Contributing factors to this growth include higher data usage on mobiledevices such as smartphones or tablets, as well as the use of data inother emerging areas such as machine-to-machine, device-to-device, orother traffic types.

Currently, significant data is provided by network operators. Forexample, data may be provided over cellular networks, such as thosedescribed by the Third Generation Partnership Project (3GPP) standards.Such mobile technologies include, but are not limited to, SecondGeneration networks such as the Global System for Mobile Communications(GSM) and Code Division Multiple Access (CDMA), Third Generationnetworks such as the Universal Mobile Telecommunications System (UMTS),and Fourth Generation networks such as Long Term Evolution (LTE). Also,Fifth Generation (5G) networks are starting to be developed. Utilizingthe technologies in these standards, network operators provide a userequipment (UE) with data services.

Wireless data is also provided in other ways, including for example, TheInstitute of Electrical and Electronic Engineers (IEEE) 802.11 standardsfor wireless local area networks (WLAN).

However, wireless spectrum is heavily utilized in many situations bynetwork operators and in order to accommodate a significant dataincrease, various options for 5G communications are being explored.

SUMMARY

One embodiment of the present disclosure provides a method at a networkelement, and a system, for resource reservation in an unlicensedspectrum band. The method includes determining quality of servicerequirements of traffic queued for a network operator. Further, themethod includes reserving resources in the unlicensed spectrum band forthe network operator in accordance with the quality of servicerequirements to form a coordination frame for the traffic, where thecoordination frame has a flexible proportion of the resources from theunlicensed spectrum.

Another embodiment of the present disclosure further provides a networkelement configured for resource reservation in an unlicensed spectrumband. The network element includes a processor configured to determinequality of service requirements of traffic queued for a cellular networkoperator. Further, the network element is configured for reservingresources in the unlicensed spectrum band for the network operator inaccordance with the quality of service requirements to form acoordination frame for the traffic, where the coordination frame has aflexible proportion of the resources from the unlicensed spectrum.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be better understood with reference to thedrawings, in which:

FIG. 1 is a block diagram showing one example network architecture;

FIG. 2 is a block diagram showing a further example network architecturein which UEs capable of communicating utilizing unlicensed spectrum areadded;

FIG. 3 is a block diagram showing logical blocks in one example ofproviding airtime shares;

FIG. 4 is a block diagram showing logical blocks for optimization ofcoexistence frames and assigning of the optimized coexistence frames inaccordance with an embodiment of the invention.

FIG. 5 is a block diagram showing the assignment of coexistence frameson the unlicensed channel in accordance with an embodiment of theinvention;

FIG. 6 is a block diagram showing options for sending NAVs at the end ofa coexistence frame in accordance with an embodiment of the invention;

FIG. 7 is a timing diagram showing an observation period, a plurality ofcoordination frames, an active sensing phase and coexistence frames inaccordance with an embodiment of the invention;

FIG. 8 is a timing diagram showing the assignment of resources during acoexistence frame in a channel in accordance with an embodiment of theinvention;

FIG. 9 is a block diagram showing a process for optimizing resources forcoexistence frames in accordance with an embodiment of the invention;

FIG. 10 is a block diagram illustrating a computing platform inaccordance with an embodiment of the invention; and

FIG. 11 illustrates a block diagram of an embodiment communicationsdevice.

DETAILED DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure provide for methods and systems toexploit unlicensed spectrum in order to ease the burden on licensedspectrum. In one aspect of the present disclosure, the use of theunlicensed spectrum also achieves target Quality of Service (QoS) andQuality of Experience (QoE) for different application scenarios andtraffic types.

In one aspect of the present disclosure, Medium Access Control (MAC)mechanisms are provided for time-frequency joint co-existence withpresent occupants of unlicensed spectrum. Such present occupants mayinclude, for example, but are not be limited to WLAN and radar systems.Specifically, an embodiment of the present disclosure provides a systemand method for efficient and flexible quality of service basedtime-domain coexistence of next-generation carrier-type air interfaceswith the existing systems in the unlicensed spectrum.

As used herein, “licensed spectrum” refers to a portion of radiofrequency spectrum exclusively granted to a licensee within a geographicarea. For example, various regulatory bodies such as the FederalCommunications Commission (FCC) and the National Telecommunications &information Administration (NTIA) in the United States may provide afrequency allocation to a licensee for a portion of the radio frequencyspectrum in a given band. Such license typically defines frequencyranges, geographic locations, maximum power levels, among otherprovisions.

“Unlicensed spectrum”, as used herein, refers to a frequency band thathas been allocated by regulatory agencies, to be available tounregistered users. That is, the unlicensed spectrum is a portion of theradio frequency spectrum without an exclusive licensee. Regulations maylimit transmission power over such unlicensed spectrum.

In one aspect, the coexistence is used by clusters of operators'transmit points (TPs), and further allows coexistence with existinglegacy and state of the art WLAN systems in the unlicensed spectrum.Specifically, exclusive soft airtime shares may be granted to a radioaccess cluster (RAC) over one or more frequency channels for a number offrames. Such frames, for example, may coexist in the time domain withother users of the unlicensed spectrum, including WLAN. The term “softairtime shares”, as used herein, indicates an allocation of a flexibleproportion of a channel's resources at a given time slot. However, theproportion of the channel utilized by the transmitter may be higher thanthe allocated amount in a given time slot to meet QoS requirements aslong as the access time is then reallocated to others utilizing thechannel and future time slots. Also, the proportion of the channelutilized by a transmitter may be lower than the allocated amount. Theterm “soft” indicates that the allocation is a longer-term targetproportion of airtime that may be implemented in a series of optimizedphysical coexistence frames.

Therefore, given a soft airtime share allocated to a TP cluster on achannel in the unlicensed spectrum within the upcoming time window, anembodiment of the present disclosure provides for dynamicallyimplementing resource reservation in the form of QoS-optimizedtime-multiplexed transmission slots forming coexistence frames.Optimization may take into account the use of unlicensed spectrum andits suitability for carrier-type air interface, the coexistenceefficiency gained by eliminating airtime loss in the form of overhead,quality of service requirements for served flows, as well as quality ofservice access categories for existing WLANs if applicable.

In one embodiment, the reservation of time-multiplex transmission slotsmay be done as part of the dynamic functionalities of a central spectrummanagement controller (CSMC) which usually handles the joint operationin both the licensed and unlicensed spectra.

Reference is now made to FIG. 1, which shows an example of two networkoperators operating in a geographic location. As seen in FIG. 1, variousbase stations 110 provide macro cell coverage for user equipments in acoverage area. Base stations 110 belong to a particular operator and inthe example of FIG. 1 some of base stations 110 may belong to the firstoperator while some of the base stations may belong to the secondoperator.

Further, a plurality of access points 112 are shown in the example ofFIG. 1. Such access points may, for example, belong to small cells suchas pico or femto cells, as well as remote radio heads (RRHs), amongothers options. Such small cells may offload some traffic from the macrocells, especially near cell boundaries or in densely used areas.

WLAN access points 114 may be utilized to offload some data traffic tothe unlicensed spectrum for a WLAN.

Further, as seen in the embodiment of FIG. 1, user equipments mayinclude devices such as laptops 120, smartphones 122, among others. Suchuser equipments may access a WLAN through a WLAN access point 114, andmay access a cellular network or a future wireless network, such aswireless network which does not have cell-IDs, through a base station110 or small cell access point 112.

Each network operator may further have a central spectrum managementcontroller (CSMC). Such controller may manage spectrum allocation fortransmission points (TPs) within the operator's network. In the exampleof FIG. 1, a CSMC 130 is operated by a first network operator and a CSMC132 is operated by a second network operator.

To increase data throughput, one option as seen from FIG. 1, is tooffload data traffic to a WLAN. However, such offloading isnon-transparent to a user and does not allow for quality of servicerequirements generally provided by a 3GPP air interface.

In this regard, in one aspect of the present disclosure, the methods andsystems port the benefits of the 3GPP air interface (AI) to theunlicensed spectrum.

The use of unlicensed spectrum for mobile communications such as 5Gcommunications (herein referred to as 5G-U for fifth generationunlicensed spectrum usage) may present several challenges. In oneembodiment, one challenge is geographically overlapping deployments ofnetworks sharing unlicensed spectrum.

Another challenge for 5G-U is that it is impractical to coordinateoperators over a common channel in the licensed spectrum or through athird party such as a brokerage. As described above, licensed spectrumusually means that the spectrum is granted to a certain network operatorand may be exclusively for this network operator to use.

Also, any solution for using unlicensed spectrum may require fairnessbetween operators and also fairness to current users of such unlicensedspectrum. For example, if the 5 GHz band is utilized for unlicensedcommunications, existing users may include WLAN applications, as well asapplications such as radar 140 from FIG. 1.

One mechanism for 5G-U usage is to perform listen before talk (LBT).However if individual transmission points (TPs) and UEs simply uselisten before talk, the time frequency resources may be unpredictableand quality of service and quality of experience may not be achieved.Further, such mechanisms do not provide for the securing of resourcesfor periodic measurements and synchronization signaling. Also, use oflisten before talk usually does not allow for advanced transmissionschemes including coordinated multipoint (CoMP) or joint transmission(JT). In a LBT system, the uplink may also be attacked due to the lowtransmission power.

Another challenge to use unlicensed spectrum is to comply with regionspecific regulations. For example, in some regions certain unlicensedspectrum may be utilized by anybody, but in other regions such spectrummay be forbidden from being used.

Therefore, in order to achieve a carrier-type air interface overunlicensed spectrum, various systems are described below. The systemsbelow will be described with regard to the 5G operations. However, thisis not meant to be limiting and the present disclosure could equally beused with other standards or transmission technologies. The use of 5G-Uis therefore only meant to be an example.

Reference is now made to FIG. 2. As seen in FIG. 2, the networks aresimilar to that of FIG. 1. In particular, a first operator has a firstarea and a second operator operates within similar geographic areas.Each utilizes base stations 210. Some of base stations 210 belong to thefirst operator while some of the base stations belong to the secondoperator.

Small cell access points 212 belong to either the first operator or thesecond operator. WLAN access points 214 can either belong to householdsor businesses or may be used by operators to provide for Wi-Fioffloading.

User equipments such as a laptop 220 or smartphone 222 may access eitherthe licensed spectrum of an operator or a WLAN through a WLAN accesspoint 214.

Further, each operator includes a CMSC, shown as CSMC 230 for a firstoperator and CSMC 232 for a second operator.

Radar 236 may be utilizing a portion of the unlicensed spectrum.

In the example of FIG. 2, UEs 234 are enabled to utilize the unlicensedspectrum for 5G-U communications in accordance with the presentdisclosure. Specifically, as seen in FIG. 2, a map of unlicensedspectrum 240 provides for a plurality of channels 242 within theunlicensed spectrum. For example channels 242 may each have 20 MHzbandwidth. However, this is merely an example and other bandwidths couldbe allocated to a channel.

Thus, the present disclosure provides for use of unlicensed spectrum for5G communications. In one aspect of the present disclosure, a softairtime grant is provided from each CSMC or virtual spectrum accesscoordinator (VSAC). The soft airtime shares may then be converted toactual frames utilizing a quality of service based dynamic optimizationof coexistence frames on self-allocated channels, as described below.

The present disclosure is not limited to any specific system or methodfor granting soft airtime shares to a TP or cluster of TPs. Varioustechniques for such grant are possible. One example of a system whichgrants soft airtime shares is described below with regard to FIG. 3.However, FIG. 3 is merely provided as an example.

Reference is now made to FIG. 3, which shows a block diagram providingan overview of the grant of soft airtime shares. As seen in FIG. 3, foreach central spectrum management controller or virtual spectrum accesscontroller, a plurality of logical blocks are provided.

A first block 320 is a multi-node passive sensing channel measurementand selection block. The multi-node passive sensing may be done by everytransmission point (TP) within a geographic area in one embodiment. Inother embodiments, the network may configure only a few TPs to do thepassive sensing. This may, for example, comprise a group of sensingnodes that perform the sensing.

The passive sensing at block 320 allows the TP to create a list ofcandidate channels. Once the passive sensing at block 320 is finished,the embodiment of FIG. 3 provides a list of the selected candidatechannels discovered during the passive sensing to a block 330.

Block 330 performs various functionality including performing an activesensing phase and creating a per-channel RAC set. Such functionalitymay, for example, be performed at the CSMC or VSAC. Specifically, atsub-block 332, each CMSC or virtual spectrum access coordinator (VSAC)configures coordinating RAC sets for each channel. Further, at sub-block334, the active sensing phase includes the reception and transmission ofbeacons. Overall, the operation of block 330 provides a way of creatingRACs and then discovering who the neighbors are for each RAC within anetwork.

Information from the passive sensing block 320 as well as the configuredper channel coordinating RAC sets from sub-block 332 are provided to aper channel coordination information block 340.

Block 340 represents the input information provided to scheduling block350, which runs schedulers for each channel. Information from theschedulers consists of exclusive soft airtime grants, which arerepresented by block 360 which is a logical block showing the outcome ofthe scheduling block allocating the soft airtime shares for eachchannel.

The soft airtime shares may then be used to provide a 5G air interfaceover the unlicensed spectrum while ensuring quality of serviceparameters.

Therefore, FIG. 3 provides one option for allocating soft airtime shareson a channel. In accordance with present disclosure, each soft airtimeshare is then converted into a frame utilizing a system and method forefficient and flexible quality of service based time-domain coexistenceof next generation carrier type air interface. In particular, thepresent disclosure dynamically implements resource reservation of thesoft airtime share in the form of QoS-optimized time-multiplexedtransmission slots forming coexistence frames. Reference is now made toFIG. 4.

As seen in FIG. 4, a QoS-based dynamic optimization of coexistenceframes block 410 provides for the dynamic optimization of frames onself-allocated channels. Specifically, block 410 provides for flexiblequality of service based time domain coexistence. By flexible, the framestructure of the 5G-U allocation is not static. Further, the quality ofservice optimization provides that the airtime is used more efficiently.In one embodiment in order to accomplish this, it is assumed that thereceivers, including TPs, within an RAC have the ability to listen toWLAN beacons.

Block 410, includes, as an input, the soft airtime share that has beenallocated to a particular RAC by a CMSC or a VSAC, shown by input 412.

Further, a joint operation block 420 provides for the joint operation inboth the licensed and unlicensed spectrums. Such joint operations block420 provides the optimization block 410 with statistical quality ofservice information, shown by arrow 422, as well as information aboutsynchronization with the licensed band transmissions, shown by block424.

Based on the inputs, dynamic optimization block 410 calculates thedeterministic physical frame allocations which are represented by thedeterministic coexistence frame block 440.

Each of the blocks are described in more detail below.

Reference is now made to FIG. 5, which shows an example of a pluralityof channels and the grant of both soft airtime shares, as well as theoptimized coexistence frames within those airtime shares. In particular,as seen in FIG. 5, a first unlicensed channel 510 is shown along with asecond unlicensed channel 512. The example of FIG. 5 is used as anillustration only and in real world embodiments, a plurality ofunlicensed channels would exist in the unlicensed spectrum.

As seen in FIG. 5, the unlicensed channel 512 is allocated to anoperator's RAC in the form of exclusive soft airtime share. Theexclusive soft airtime share span a coordination period that includesboth an active sensing phase 520, along with a remainder of thecoordination period for allocation of one or more of coexistence frames.

In any given coordination period 530, the soft airtime provides aproportion of the airtime to the existing users of the unlicensedspectrum, such as WLAN. It also provides airtime to one of various RACs.In the example of FIG. 5, in a first coordination time period, the WLANreceives an allocation of 65% of the airframe, shown by block 532. TheRAC then receives the remaining 35% allocation shown by block 534.

Similarly, in a second coordination time period 540, the WLAN receives40% of the allocation, shown by block 542. A different RAC than in thefirst time slot receives an allocation of 60% of the airtime, shown byblock 544.

In FIG. 5, the example of channel 512 does not provide for the actualallocation of the coexistence frames. However, based on optimizationblock 410 above, the coexistence frames may be allocated. Suchallocation is shown with regard to channel 510 in the embodiment of FIG.5.

In particular, in the embodiment of FIG. 5 a coordination time frame 550is provided with a soft airtime allocation which includes 37% for a WLANas shown by block 552 and 63% for the RAC as shown by block 554.

The allocation is then optimized to create actual frames. These areshown, for example, by frames 562, 564, and 566. Further, coordinationperiod 550 includes an active sensing phase block 568 within thecoordination period. In one embodiment, as shown in FIG. 5, coexistenceframe 564 only includes resources from the 5G network. As an alternativeembodiment, a coexistence frame may only include resource from a WLANnetwork.

The optimization of frame allocation by block 410 of FIG. 4 above allowsfor flexibility in terms of the coexistence frames. Thus, the frameallocation is not restricted to a fixed carrier frame size. Nor is theassigned frame restricted to a WLANs beacon interval, also known astarget beacon transmission time (TBTT). By allowing for flexible framesize, airtime may be optimized. Specifically, no loss of airtime orcoexistence overhead is incurred since the flexible timing allows forthe controller to seize unused airtime.

Further, optimization takes into account the delay budget of packets ina queue for the 5G air interface. It also considers the maximum durationfor measurement, synchronization and control for 5G-U packets. Further,the optimization considers the WLAN's enhanced distributed channelaccess (EDCA) requirements for successful transmission.

As described below, before any coexistence frame and time, a transmitpoint listens and grabs a channel before the WLAN. It then reserves theoptimized portion of the following coexistence frames using a multi-nodetransmission of a fake WLAN clear to send (CTS) signal. If an RAC hasmultiple TPs, such transmission of the CTS signal may either be jointbetween TPs within an RAC or it may be sequential, depending on thesystem design.

Referring again to FIG. 5, in a second time frame 580 the WLAN isallocated 60% of the airframe, shown by block 582 and the RAC isallocated 40% of the airframe, as shown by block 584. In this case,various frames are allocated, wherein the frames are optimized for usein the coordination time period 580, such optimized frames are shownwith references 586, 587 and 588.

The frames in the unlicensed spectrum used for the 5G airframe can thenutilize similar techniques as those used for the licensed spectrum for5G. In particular, as shown in FIG. 5, during the optimized airframe,techniques such as coordinated multipoint (CoMP) transmission of datamay be provided to a UE, while control signaling is provided from amacro base station, shown by block 590. Block 590 further provides forother optimization of transmission and spectrum utilization, includingdevice to device (D2D) communications on the unlicensed spectrum.

Similarly, block 592 shows the usage by a different operator and RAC ofsimilar techniques.

Based on the above, the optimization at block 410 has variousfunctionalities. In a first aspect, the optimization maximizes thelength of the upcoming coexistence frames while taking into accountvarious considerations. A first consideration is the timing requirementsfor control measurements and synchronization of the operators airinterface. Thus, in accordance with the first consideration, adequatetiming needs to be allocated to ensure that periodic carrier-typecontrol, measurement and synchronization signaling may be doneeffectively.

A second consideration for maximizing the length of the flexiblecoexistence frame is the current quality of service requirements ofoperator packets that are in queues. In other words, packet delaybudgets are taken into account with regard to the length of upcomingcoexistence frames.

A third consideration may include factoring the most stringent WLAN QoSrequirements by detecting access categories (ACs) being served in thevicinity. Such consideration is only relevant for state of the artWLANs, such as 802.11e or 802.11ac WLANs. In other cases, default valuesmay be used for WLAN QoS requirements.

A fourth consideration for maximizing the length is equalizing the WLANsfraction of airtime for upcoming coexistence frames based on the actualairtime within the elapsed frames in order to maintain an overall ratioof operator to WLAN airtime shares. In other words, if, due to qualityof service requirements, a higher proportion than allocated was used bythe RAC in a previous coexistence frame, then a subsequent coexistenceframe may compensate for the overuse by assigning more resources to theWLAN.

In order to seize the airtime resources, in one aspect of the presentdisclosure, an RAC may send a multi-node transmission of fake WLANCTS/Request to Send (RTS) frames to effectively clear the medium fromsurrounding WLAN transmissions. If the RAC includes multiple TPs, suchmulti-node transmissions may either be joint, wherein all of the TPswithin the RAC send the fake WLANs CTS/RTS jointly, or may besequential. If only one TP exists within the RAC, the WLAN CTS/RTS issent from the TP to clear the medium. The fake WLAN CTS/RTS framesprotect the optimized duration of the cluster's upcoming time slot bysetting the network allocation vectors (NAVs) for the WLAN to force thedeferral of contention. The NAVs will preclude, for the time period setin the vector, the WLAN from contending for the channel resources.

In a further aspect, the medium may be acquired close to the end of thecoexistence frame after the WLAN has finished transmitting. In thiscase, the remaining time period within that WLAN transmission slot maybe insufficient for another successful WLAN transmission. In this case,the time may be granted to a 5G-U air interface. In other words, if theWLAN transmission is close to the end of its frame and there isinsufficient resources for another WLAN to transmit then the RAC mayopportunistically seize the resources of the channel utilizing the fakeWLAN CTS/RTS.

In a further aspect of the present disclosure, symbol levelsynchronization of the transmissions within the optimized slots in theunlicensed band conforms with existing signals on the licensed band.This may be based on a signal from a joint operation manager within theoperator's network to align the physical symbols in both bands, allowingfor a unified air interface.

Reference is now made to FIG. 6, which shows transmission blocks withina co-existence period. As seen in FIG. 6, a coexistence frame 610 formspart of a coordination period. In the example of FIG. 6, thecoordination period dynamically allocates, through soft airtime shares,the WLAN to have 65% of the resources while a first RAC has 35% of theresources during the coordination period.

After the active sensing phase 612, the 5G-U channel is seized throughthe issuance of the CTS/RTS with the NAVs set for a particular duration.This is shown by block 620.

After the transmission at block 620, the 5G-U has the channel for theduration set within the NAVs. Therefore, in block 624 the 5G-U mayperform downlink and uplink transmissions in a similar manner to the airinterface of the licensed 5G spectrum. The time within block 624 may beutilized, for example, to offload data from the licensed spectrum to theunlicensed spectrum and to utilize the air interface to optimize suchdata transfer.

At the end of block 624, the WLAN is granted access to the channel, asshown by block 626. The actual granted time is defined by the formula(1−SAT_(2.1, n)) T_(coex)(t,0), where SAT_(2.1,n) is the granted softairtime percentage for 5G-U communications, and is realized after thecoexistence frame elapses.

Prior to the expiration of the coexistence frame, the network elementagain takes control of the channel through the issuance of the CTS/RTSwith the NAVs set for a particular duration. If, as shown by block 626,the transmission ends prior to the maximum transmission opportunity thena time period, shown by block 628, remains for the WLAN allocation. Inone embodiment, shown by reference 630, the RAC may wait until the endof maximum transmission opportunity prior to sending the NAVs. Thus, theNAVs are sent as shown by blocks 632.

After sending the NAVs, then a further time slot, shown by block 636 maybe used for 5G-U transmissions.

Alternatively, as shown by reference 640, the NAVs may be sent early.This would happen if, for example, the WLAN transmission continuedthrough the maximum transmission opportunity and hence the remainingtime at block 628 was not long enough to have another complete WLANtransmission. In this case, as shown by reference 640, the NAVs are sentearly, shown by blocks 642, and then the 5G-U transmission utilizes thechannel, as shown by block 644.

In a further alternative embodiment, shown by reference 650 the NAVs maybe sent jointly. Thus, the NAV transmission is shown by block 652. Afterthe NAV transmission, the channel may be utilized for 5G-U transmissionsshown by block 654.

In the above, if the NAVs are sent sequentially, then the NAV settingsignals are spaced by a time that is less than the point coordinationfunction (PCF) interframe spacings (PIFS).

If the NAVs are sent early, the optimization utilizes the channel moreefficiently since the WLAN deficit is captured by the 5G-Utransmissions. An attempt to compensate for the WLAN's deficit may bemade while optimizing the following CoexFrame.

Reference is now made to FIG. 7, which shows the breakdown of a softairtime allocation. FIG. 7 shows the timeline of the observation andcoordination time scales, along with the active sensing phases describedabove. As seen in FIG. 7, both long and short term observation periodsare provided. In particular, a long observation period, denoted T_(obs),is utilized for passive observation of the channels to ensure that thesoft airtime is allocated appropriately and on appropriate channels. Ashorter time scale, denoted as T_(coord) is utilized for the sensingphase as well as the creation of RACs and access to the channel througha soft airtime grant. In FIG. 7, the T_(obs) time period 710 is shown tobe much longer than the T_(coord) time period 720.

Further, as seen in FIG. 7, during the T_(coord) time period 720, anactive sensing phase 730 and a plurality of coexistence frames 740exist. The active sensing phase 730 is used by RACs to provide beaconsto neighboring RACs, allowing RACs to compile a list of neighbors andattributes of the neighbors. One this procedure is finished, an RAC maybe granted access to the coexistence frames in accordance with the softairtime grant.

Referring to FIG. 8, the dynamic optimization of the coexistence framesfor a quality of service based distribution of the soft airtime share isprovided. The example of FIG. 8 is one example showing the allocation ofthe airtime grant to accommodate both the 5G-U air interface and thequality of service requirements thereof, as well as the WLAN interfaceand its quality of service requirements.

In the embodiment of FIG. 8, two coexistence frames, namely coexistentframe 810 and coexistent frame 812 are provided. The time periods forthe coexistence frames are denoted as T_(coex) (t,i) for coexistenceframe 810 and T_(coex) (t,i+1) for coexistence frame 812.

In the example of FIG. 8, each coexistence frame includes both a 5G-Utransmission as well as a WLAN transmission. In coexistence frame 810,the 5G-U transmission is shown with reference numeral 820 and the WLANtransmission is shown with reference numeral 822.

Each coordination period consists of the active sensing phase plus thecoexistence frames. This may be noted in accordance with equation 1below.

$\begin{matrix}{{\sum\limits_{j}\; {T_{Coex}\left( {t,j} \right)}} = {T_{Coord} - T_{A\; S\; P}}} & (1)\end{matrix}$

As seen in equation 1 above, the sum of all the coexistence periods isequal to the coordination period minus the period for the active sensingphase.

Within each coordination frame, the portion allocated to the 5G-Utransmission is denoted by SAT_(l,n)(t). The target WLAN SAT istherefore denoted by equation 2 below.

λ(t,0)=1−SAT_(l,n)(t)  (2)

In some cases not all of the actual target WLAN SAT is used by the WLAN.For example, in FIG. 8, the WLAN transmission period 822 is shown to beT_(w,Actual)(t, i) as denoted by reference numeral 824, and is less thanthe actual soft airtime allocation for the WLAN, as shown by referencenumeral 826.

Further, once the transmission time ends, the RAC may send its NAVs asshown by block 830.

One parameter within the optimization algorithm ensures that the amountof time allocated for the WLAN meets minimum thresholds. Specifically,the WLAN transmission in the upcoming coexistence frame must not violatea minimum packet delay budget. This is shown, for example, with regardto equation 3 below, which shows that the length of the coexistenceframe multiplied by the allocation to the WLAN, when added to the timefor the NAV setting must be less than the minimum packet delay budget,where the value of the WLANs allocation falls between 0 and 1.

$\begin{matrix}{{{{{\lambda \left( {t,i} \right)}{T_{Coex}\left( {t,i} \right)}} + T_{SetNAVs}} < {\min\limits_{k \in K_{l}}\left\{ {P\; D\; {B_{k,l}\left( {t,i} \right)}} \right\}}},{0 \leq {\lambda \left( {t,i} \right)} \leq 1}} & (3)\end{matrix}$

A further consideration for the optimization is that the intervalbetween 5G-U slots should support reference and measurement signals.This may be shown, for example with regard to equation 4 below.

T _(Coex)(t,i)<τ_(meas) _(_) _(max) ^(SG-U)  (4)

As seen in equation 4 above, the default coexistence frame size, denotedT_(Coex) (t, i) must be less than the maximum time required forreference and measurement signals.

In a further aspect of the optimization, the WLANs transmission in anupcoming coexistence frame should be sufficient to allow for contentionand the longest enhanced distributed channel access (EDCA) transmissionopportunity. This is, for example, shown below with regard to equation5.

DIFS+CW _(max)+maxTXOP≦λ(t,i)T _(Coex)(t,i), λ(t,i)>0  (5)

As seen in equation 5 above, the distributed interframe space (DIFS),plus the maximum contention window (CW_(max)) plus the maximumtransmission opportunity, should be less than or equal to the proportionof the coexistence frame allocated for the WLAN, where at least aportion of the subframe is allocated for the WLAN, denoted by λ(t, i),is greater than 0.

A further consideration for the optimization is to compensate the WLANin situations where the 5G-U has taken more airtime than allocated forquality of service reasons. Such equalization, for example, may be shownwith regard to equation 6 below.

$\begin{matrix}{{{{\lambda \left( {t,{i + 1}} \right)}{T_{Coex}\left( {t,{i + 1}} \right)}} + {\sum\limits_{j = 0}^{i}\; {T_{w,{Actual}}\left( {t,j} \right)}}} = {{\lambda \left( {t,0} \right)}\left\lbrack {{T_{Coex}\left( {t,{i + 1}} \right)} + {\sum\limits_{j = 0}^{i}{T_{Coex}\left( {t,j} \right)}}} \right\rbrack}} & (6)\end{matrix}$

As seen in equation 6, the percentage of the channel allocated in acoexistence frame number i+1, plus the sum of actual allocations for theWLAN in past subframes, should equal the target WLAN SAT times the sumof the next coexistence time frame and the sum of the past coexistenceframes.

In a further optimization parameter, dead airspace that would be uselessto the WLAN because the time period left is too short for the WLAN canbe used for the 5G-U transmission. Alternatively, the whole time framemay be given to the WLAN if the target SAT has been violated due to the5G-Us quality of service requirements. This is shown by equation 7below.

$\begin{matrix}{{\lambda \left( {t,{i + 1}} \right)} = \left\{ \begin{matrix}{0,} & {T_{Coord\_ end} < {{D\; I\; F\; S} + {C\; W_{\max}} + {\max \; T\; X\; O\; P}}} \\{1,} & {{\sum\limits_{j = 0}^{i}{{T_{w,{Actual}}\left( {t,j} \right)}/\left( {T_{Coord} - T_{A\; S\; P} - T_{{Coord}_{end}}} \right)}}{\lambda \left( {t,0} \right)}}\end{matrix} \right.} & (7)\end{matrix}$

As seen in equation 7 above, the proportion of the next subframe for theWLAN is 0 if the time for the coordination is less than a thresholdtime, and is 1 if the actual use of the WLAN is much less than theproportion allocated by the soft airframe grant.

The above may be summarized in accordance with the process diagram ofFIG. 9. Referring to FIG. 9, the example process starts at block 910 inwhich the maximum transmission opportunity, the contention window, andpotentially other factors are configured based on the detected WLANquality of service ACs. The process then proceeds to block 920 in whichvarious initializations are performed. In a first initialization, theWLAN SAT is set. Further the maximum coexistence frame size is set,along with the default coexistence size.

From block 920 the process proceeds to block 930 in which the nextcoexistence frame size is set to be the minimum of the coexistence framesize and the smallest packet delay budget minus the time for the settingof the NAVs divided the SAT of the WLAN.

Once the coexistence frame size has been set in block 930, the processproceeds to block 940 in which a check is made to determine whether theend of the last WLAN transmission has occurred. If not, the processproceeds to loop to block 940 until the end of the WLAN transmission isfound. At this point, the process proceeds to block 942 in which the endof the coordination period is calculated, as well as the actualtransmission time used for WLAN.

The process then proceeds to block 944 in which the counter isincremented for the coexistent frame and the process then proceeds toblock 946 in which a check is made to determine whether or not the endof the coordination period is less than the DIFS+CW_(max) plus themaximum transmission opportunity. This determines whether the timeperiod remaining is too little to make further WLAN transmissions.

If the time is too short then the process proceeds from block 946 to948. At block 948, the allocation to the WLAN is set to 0 and theprocess then proceeds to block 950 in which the coexistence frame timeperiod is set to the end of the coordination period and the process thenproceeds to block 952 and ends.

From block 946, if there is sufficient time for the WLAN then theprocess proceeds to block 960 in which a check to determine whether ornot the actual allocation to the WLAN is much less than the grantedallocation. If yes, then the process proceeds to block 962 in which theWLAN is granted the entire next coordination frame. From block 962 theprocess proceeds to block 950 which ends the coexistence frame and theprocess then proceeds to block 952 and ends.

From block 960, if the allocation is not much less than the grantedallocation then the process proceeds to block 964 in which a minimumtime required for the WLAN transmission is set and the process thenproceeds to block 966. At block 966, a check is made to determine theDIFS+CW_(max) plus the maximum transmission opportunity is less than theminimum transmission requirement. If no, then the process proceeds toblock 968 in which the WLAN SAT is set to zero, and the process thenproceeds to block 970.

At block 970 the size of the coexistence time frame is set to theremaining time period and the process then proceeds back to block 942.

From block 966, if there is sufficient time to allocate time to the WLANthen process proceeds to block 980 in which the coexistence frame periodis calculated. At block 982 the coexistence time period is set to theminimum of the coexistence time period calculated at block 980 and thetime until the end of the coordination period.

The process then proceeds to block 984 in which a check is made todetermine whether or not the time allocated is greater than 0. If yes,then the proportion of the frame allocated to the WLAN is set at block986 and the process proceeds back to block 940.

Conversely, if the coexistence period is not greater than 0 then fromblock 984 the process proceeds to block 990 in which the SAT for thenext time period for the WLAN is set to the default SAT value and thecoexistence frame time for the next time frame is set to be theremainder. From block 990 the process proceeds back to block 940 andends.

The above therefore provides for time domain coexistence of clusters ofTPs rather than for individual base stations.

The above further provides for a flexible, rather than a static,superframe, size. This eliminates airtime overhead and it provides theflexibility to meet quality of service requirements.

In order to seize the channel, geographically spread fake WLAN framesmay be transmitted through multi-node transmission in a coexistingcluster. Such transmissions may either be joint or sequential in time,and provide effective protection from WLAN transmissions, especially forthe uplink where power levels may not be detected by the WLAN.

The above further provides for optimization of length of the upcomingflexible coexistence frames. In particular, considering the maximumtiming requirements for control, measurements, and synchronization ofthe operator air interface is done. Further, a consideration of thecurrent quality of service requirements for operator packets in queuesis made to ensure packet delay budgets are met.

By optimizing the length of the upcoming coexistence frame, the moststringent WLAN QoS service requirements may be met by ensuring that theaccess categories are detected and are being served in the vicinity forWLANs that support such access categories.

Further, equalization of a WLAN's fraction of airtime in the upcomingcoexistence frame based on the actual airtime within the elapsed framesmaintains an overall ratio of operator to WLAN airtime shares, thusensuring the fairness of the 5G-U transmissions.

In a further aspect, the optimization allows for enabling unifiedcarrier type air interfaces by symbol level synchronization withtransmissions in the licensed bands.

The above functionality may be implemented on any one or combination ofnetwork elements. FIG. 10 is a block diagram of a processing system 1000that may be used for implementing the devices and methods disclosedherein. Specific devices may utilize all of the components shown, oronly a subset of the components, and levels of integration may vary fromdevice to device. Furthermore, a device may contain multiple instancesof a component, such as multiple processing units, processors, memories,transmitters, receivers, etc. The processing system 1000 may comprise aprocessing unit equipped with one or more input/output devices, such asa speaker, microphone, mouse, touchscreen, keypad, keyboard, printer,display, and the like. The processing unit may include a centralprocessing unit (CPU) 1010, memory 1020, a mass storage device 1030, avideo adapter 1040, and an I/O interface 1050 connected to a bus 1060.

The bus 1060 may be one or more of any type of several bus architecturesincluding a memory bus or memory controller, a peripheral bus, videobus, or the like. The CPU 1010 may comprise any type of electronic dataprocessor. The memory 1020 may comprise any type of system memory suchas static random access memory (SRAM), dynamic random access memory(DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), a combinationthereof, or the like. In an embodiment, the memory may include ROM foruse at boot-up, and DRAM for program and data storage for use whileexecuting programs.

The mass storage device 1030 may comprise any type of storage deviceconfigured to store data, programs, and other information and to makethe data, programs, and other information accessible via the bus. Themass storage device 1030 may comprise, for example, one or more of asolid state drive, hard disk drive, a magnetic disk drive, an opticaldisk drive, or the like.

The video adapter 1040 and the I/O interface 1050 provide interfaces tocouple external input and output devices to the processing unit. Asillustrated, examples of input and output devices include the display1042 coupled to the video adapter and the mouse/keyboard/printer 1052coupled to the I/O interface. Other devices may be coupled to theprocessing unit, and additional or fewer interface cards may beutilized. For example, a serial interface such as Universal Serial Bus(USB) (not shown) may be used to provide an interface for a printer.

The processing unit 1000 also includes one or more network interfaces1070, which may comprise wired links, such as an Ethernet cable or thelike, and/or wireless links to access nodes or different networks. Thenetwork interface 1070 allows the processing unit to communicate withremote units via the networks. For example, the network interface 1070may provide wireless communication via one or more transmitters/transmitantennas and one or more receivers/receive antennas. In an embodiment,the processing unit 1000 is coupled to a local-area network or awide-area network, shown as network 1072, for data processing andcommunications with remote devices, such as other processing units, theInternet, remote storage facilities, or the like.

FIG. 11 illustrates a block diagram of an embodiment of a communicationsdevice 1100, which may be equivalent to one or more devices (e.g., UEs,NBs, etc.) discussed above. The communications device 1100 may include aprocessor 1104, a memory 1106, a cellular interface 1110, a supplementalwireless interface 1112, and a supplemental interface 1114, which may(or may not) be arranged as shown in FIG. 11. The processor 1104 may beany component capable of performing computations and/or other processingrelated tasks, and the memory 1106 may be any component capable ofstoring programming and/or instructions for the processor 1104. Thecellular interface 1110 may be any component or collection of componentsthat allows the communications device 1100 to communicate using acellular signal, and may be used to receive and/or transmit informationover a cellular connection of a cellular network. The supplementalwireless interface 1112 may be any component or collection of componentsthat allows the communications device 1100 to communicate via anon-cellular wireless protocol, such as a Wi-Fi or Bluetooth protocol,or a control protocol. The device 1100 may use the cellular interface1110 and/or the supplemental wireless interface 1112 to communicate withany wirelessly enabled component, e.g., a base station, relay, mobiledevice, etc. The supplemental interface 1114 may be any component orcollection of components that allows the communications device 1100 tocommunicate via a supplemental protocol, including wire-line protocols.In embodiments, the supplemental interface 1114 may allow the device1100 to communicate with another component, such as a backhaul networkcomponent.

Through the descriptions of the preceding embodiments, the teachings ofthe present disclosure may be implemented by using hardware only or byusing a combination of software and hardware. Software or other computerexecutable instructions for implementing one or more embodiments, or oneor more portions thereof, may be stored on any suitable computerreadable storage medium. The computer readable storage medium may be atangible or in transitory/non-transitory medium such as optical (e.g.,CD, DVD, Blu-Ray, etc.), magnetic, hard disk, volatile or non-volatile,solid state, or any other type of storage medium known in the art.

Additional features and advantages of the present disclosure will beappreciated by those skilled in the art.

The structure, features, accessories, and alternatives of specificembodiments described herein and shown in the Figures are intended toapply generally to all of the teachings of the present disclosure,including to all of the embodiments described and illustrated herein,insofar as they are compatible. In other words, the structure, features,accessories, and alternatives of a specific embodiment are not intendedto be limited to only that specific embodiment unless so indicated.

Moreover, the previous detailed description is provided to enable anyperson skilled in the art to make or use one or more embodimentsaccording to the present disclosure. Various modifications to thoseembodiments will be readily apparent to those skilled in the art, andthe generic principles defined herein may be applied to otherembodiments without departing from the spirit or scope of the teachingsprovided herein. Thus, the present methods, systems, and or devices arenot intended to be limited to the embodiments disclosed herein. Thescope of the claims should not be limited by these embodiments, butshould be given the broadest interpretation consistent with thedescription as a whole. Reference to an element in the singular, such asby use of the article “a” or “an” is not intended to mean “one and onlyone” unless specifically so stated, but rather “one or more”. Allstructural and functional equivalents to the elements of the variousembodiments described throughout the disclosure that are known or latercome to be known to those of ordinary skill in the art are intended tobe encompassed by the elements of the claims.

Furthermore, nothing herein is intended as an admission of prior art orof common general knowledge. Furthermore, citation or identification ofany document in this application is not an admission that such documentis available as prior art, or that any reference forms a part of thecommon general knowledge in the art. Moreover, nothing disclosed hereinis intended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims.

1. A method at a network element for resource reservation in anunlicensed spectrum band, the method comprising: determining quality ofservice requirements of traffic queued for a network operator; andreserving resources in the unlicensed spectrum band for the networkoperator in accordance with the quality of service requirements to forma coordination frame for the traffic, wherein the coordination framecomprises a flexible proportion of the resources from the unlicensedspectrum.
 2. The method of claim 1, wherein the coordination framecomprises at least one flexible sized coexistence frame.
 3. The methodof claim 2, wherein the resources in the coexistence frame are timemultiplexed with resources of other users of the unlicensed spectrumband.
 4. The method of claim 3, wherein the resources of other users inthe unlicensed spectrum include resources for a wireless local areanetwork, and wherein the determining quality of service requirementfurther includes determining quality of service requirements of thetraffic for wireless local area network.
 5. The method of claim 1,wherein the determining quality of service requirement includesdetermining a delay budget of packets in a queue for the networkoperator.
 6. The method of claim 1, wherein the flexible sizedcoexistence frame comprises resources from at least one of the networkoperator and the wireless local area network.
 7. The method of claim 6,wherein the network element takes control of a frame prior to expiry ofprevious coexistence frame.
 8. The method of claim 7, wherein thenetwork element takes control by instructing sending a networkallocation request from a transmission point on the unlicensed spectrumband prior to expiry of the previous coexistence frame.
 9. The method ofclaim 7, wherein the network element takes control by instructingsending a network allocation request from a plurality of transmissionpoints in a cluster of transmission points on the unlicensed spectrumband prior to expiry of the previous coexistence frame, and wherein thenetwork allocation request is sent jointly by a plurality oftransmission points in the cluster of transmission points.
 10. Themethod of claim 7, wherein the network element takes control byinstructing sending a network allocation request from a plurality oftransmission points in a cluster of transmission points on theunlicensed spectrum band prior to expiry of the previous coexistenceframe, and wherein the network allocation request is instructed to besent sequentially by a plurality of transmission points in the clusterof transmission points.
 11. The method of claim 8, wherein the networkallocation request is instructed to be sent prior to an end of a maximumwireless local area network transmission opportunity if the actualwireless local area network transmission time is less than maximumwireless local area network transmission opportunity.
 12. The method ofclaim 6, wherein the coexistence frame is allocated based on a timeremaining in the coordination frame, wherein if insufficient time isremaining for a wireless local area network transmission, thecoexistence frame is allocated to the network operator.
 13. The methodof claim 6, wherein the coexistance frame is sized to ensure a wirelesslocal area network's transmission meets a minimum packet delay budgetwhen the coexistence frame comprises resources from the wireless localarea network.
 14. The method of claim 1, wherein reserving resourcesincludes compensating a wireless local area network if a share ofresources previously used by the network operator in the spectrum bandis greater than resources allocated to the network operator.
 15. Themethod of claim 1, wherein an interval between reservations of resourcesfor the network operator is adequate to maintain periodic carrier-typereference and measurement signals by the network operator.
 16. Themethod of claim 1, wherein the reserving resources allows symbol levelsynchronization with transmissions in a licensed spectrum band.
 17. Anetwork element configured for resource reservation in an unlicensedspectrum band, the network element comprising a processor configured to:determine quality of service requirements of traffic queued for anetwork operator; and reserve resources in the unlicensed spectrum bandfor the network operator in accordance with the quality of servicerequirements to form a coordination frame for the traffic, wherein thecoordination frame comprises a flexible proportion of the resources fromthe unlicensed spectrum.
 18. The network element of claim 17, whereinthe coordination frame comprises at least one flexible sized coexistenceframe.
 19. The network element of claim 18, wherein the resources in thecoexistence frame are time multiplexed with resources of other users ofthe unlicensed spectrum band.
 20. The network element of claim 19,wherein resources of the other users in the unlicensed spectrum includeresources for a wireless local area network, and wherein the determiningquality of service further includes determining quality of servicerequirements of the traffic for wireless local area network.
 21. Thenetwork element of claim 17, wherein the determining quality of serviceincludes determining a delay budget of packets in a queue for thenetwork operator.
 22. The network element of claim 17, wherein theflexible sized coexistence frame comprises resources from at least oneof the network operator and the wireless local area network.
 23. Thenetwork element of claim 22, wherein the network element takes controlof a frame prior to expiry of previous coexistence frame.
 24. Thenetwork element of claim 23, wherein the network element takes controlby instructing sending a network allocation request from a transmissionpoint on the unlicensed spectrum band prior to expiry of the previouscoexistence frame.
 25. The network element of claim 23, wherein thenetwork element takes control by instructing sending a networkallocation request from a plurality of transmission points in a clusterof transmission points on the unlicensed spectrum band prior to expiryof the previous coexistence frame, and wherein the network allocationrequest is instructed to be sent jointly by a plurality of transmissionpoints in the cluster of transmission points.
 26. The network element ofclaim 23, wherein the network element takes control by instructingsending a network allocation request from a plurality of transmissionpoints in a cluster of transmission points on the unlicensed spectrumband prior to expiry of the previous coexistence frame, and wherein thenetwork allocation request is instructed to be sent sequentially by aplurality of transmission points in the cluster of transmission points.27. The network element of claim 24, wherein the network allocationrequest is sent prior to an end of a maximum wireless local area networktransmission opportunity if the actual wireless local area networktransmission time is less than maximum wireless local area networktransmission opportunity.
 28. The network element of claim 22, whereinthe coexistence frame is allocated based on a time remaining in thecoordination frame, wherein if insufficient time is remaining for awireless local area network transmission, the coexistence frame isallocated to the network operator.
 29. The network element of claim 22,wherein the coexistance frame is sized to ensure a wireless local areanetwork's transmission meets a minimum packet delay budget when thecoexistence frame comprises resources from the wireless local areanetwork.
 30. The network element of claim 17, wherein the networkelement is configured to reserve resources by compensating a wirelesslocal area network if a share of resources previously used by thenetwork operator in the spectrum band is greater than resourcesallocated to the network operator
 31. The network element of claim 17,wherein an interval between reservations of resources for the networkoperator is adequate to maintain periodic carrier-type reference andmeasurement signals by the network operator.
 32. The network element ofclaim 17, wherein the network element is configured to reserve resourcesto allow symbol level synchronization with transmissions in a licensedspectrum band.